<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style> 
    .div{
        display: flex;
        width: 60%;
        height: 300px;
        background-color: pink;
    }
    .div div:nth-child(1){
         flex-grow: 1;
       background-color: aqua;
    }
    .div div:nth-child(2){
          flex: 2;
          background-color: palegoldenrod;
    }
    .div div:nth-child(3){
        flex: 1;
        background-color: black;
    }
    </style>
</head>
<body>
    <div class="div">
        <div>1</div>
        <div>2</div>
        <div>3</div>
      </div>  
</body>
</html>